全文获取类型
收费全文 | 20576篇 |
免费 | 2228篇 |
国内免费 | 1160篇 |
专业分类
电工技术 | 1396篇 |
综合类 | 1720篇 |
化学工业 | 3131篇 |
金属工艺 | 956篇 |
机械仪表 | 1098篇 |
建筑科学 | 1501篇 |
矿业工程 | 437篇 |
能源动力 | 437篇 |
轻工业 | 2883篇 |
水利工程 | 519篇 |
石油天然气 | 630篇 |
武器工业 | 142篇 |
无线电 | 2211篇 |
一般工业技术 | 2239篇 |
冶金工业 | 786篇 |
原子能技术 | 279篇 |
自动化技术 | 3599篇 |
出版年
2024年 | 137篇 |
2023年 | 418篇 |
2022年 | 863篇 |
2021年 | 1012篇 |
2020年 | 810篇 |
2019年 | 704篇 |
2018年 | 702篇 |
2017年 | 882篇 |
2016年 | 755篇 |
2015年 | 1099篇 |
2014年 | 1290篇 |
2013年 | 1538篇 |
2012年 | 1689篇 |
2011年 | 1736篇 |
2010年 | 1520篇 |
2009年 | 1414篇 |
2008年 | 1389篇 |
2007年 | 1211篇 |
2006年 | 1105篇 |
2005年 | 879篇 |
2004年 | 570篇 |
2003年 | 399篇 |
2002年 | 316篇 |
2001年 | 286篇 |
2000年 | 237篇 |
1999年 | 180篇 |
1998年 | 123篇 |
1997年 | 88篇 |
1996年 | 81篇 |
1995年 | 64篇 |
1994年 | 46篇 |
1993年 | 44篇 |
1992年 | 48篇 |
1991年 | 20篇 |
1990年 | 32篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 19篇 |
1986年 | 23篇 |
1985年 | 14篇 |
1984年 | 22篇 |
1983年 | 15篇 |
1982年 | 15篇 |
1981年 | 8篇 |
1980年 | 22篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1974年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Dan Ye Kaiyu Wang Haijiao Yang Xingang Zhao 《International Journal of Adaptive Control and Signal Processing》2020,34(11):1677-1696
In this article, an adaptive fuzzy output feedback control method is presented for nonlinear time-delay systems with time-varying full state constraints and input saturation. To overcome the problem of time-varying constraints, the integral barrier Lyapunov functions (IBLFs) integrating with dynamic surface control (DSC) are applied for the first time to keep the state from violating constraints. The effects of unknown time delays can be removed by using designed Lyapunov-Krasovskii functions (LKFs). An auxiliary design system is introduced to solve the problem of input saturation. The unknown nonlinear functions are approximated by the fuzzy logic systems (FLS), and the unmeasured states are estimated by a designed fuzzy observer. The novel controller can guarantee that all signals remain semiglobally uniformly ultimately bounded and satisfactory tracking performance is achieved. Finally, two simulation examples illustrate the effectiveness of the presented control methods. 相似文献
4.
采用ETAG 004:2013《外墙外保温薄抹灰系统欧洲技术认证指南》中规定的静态泡沫块法,测试在单位面积上使用不同数量锚栓的岩棉板外保温系统的抗风压性能。通过试验可以得出:在混凝土墙体上单纯采用敲击式锚栓锚固岩棉板外保温系统时,拉伸强度可达12.9 k Pa;单位面积增加锚栓的使用量可以提高系统的抗拉承载力,但在不同条件下增加相同数量锚栓对系统抗风载能力提高的程度不同;在普通混凝土墙中,单纯锚固岩棉板保温系统破坏时,单个锚栓承载力平均值的最大值约为其拉拔承载力的50.3%。 相似文献
5.
There are many potential causes of corrosion in animal buildings. Animals exhale large quantities of moisture into the air creating high relative humidity in the building if the moisture is not properly vented. High humidity increases the potential for condensation. In addition, ammonia may be found in large quantities in animal buildings. Ammonia is released from manure and urine. In addition, ammonium chloride is used as a nitrogen source in fertilisers. In this study, the atmospheric corrosion of hot-dip-galvanised steel and zinc alloy-coated steel such as zinc–aluminium and zinc–aluminium–magnesium has been studied in atmospheres containing different levels of ammonia. Investigations have also been conducted at different levels of ammonium chloride. The results are discussed in view of the mechanisms of corrosion of zinc and zinc alloy-coated steel in ammonia and ammonium chloride-containing environments. 相似文献
6.
Elucidation of colour development and microstructural characteristics of Allium sativum fumigated with acetic acid 下载免费PDF全文
Li Li Dan Wang Xihong Li Yu Wang Xiaofeng Ju 《International Journal of Food Science & Technology》2015,50(5):1083-1088
It has been well known that the greening of Allium sativum cloves could be formed after immersed in acetic acid solution. Nonetheless, no investigation was reported on colour development of A. sativum in response to acetic acid vapour until now. In this study, the brief exposure of A. sativum to acetic acid vapour (200–400 ppm) was combined with controlled atmosphere (5%, 20% and 80% CO2) packaging storage to break cell membrane and green garlic. The garlic bulbs were fumigated with acetic acid before controlled CO2 atmosphere packaging for 25 days at 4 °C. Fumigation with 200 ppm acetic acid followed by high CO2 atmosphere packaging (80% CO2) facilitated the garlic greening. It was also verified that γ‐glutamyl transpeptidase was involved in garlic greening in present study, and the compromise of glacial acetic acid vapour fumigation and CO2 gas atmosphere in package stored at low temperature could result in garlic greening as well. 相似文献
7.
针对郭庄煤业选煤厂振动筛振动筛分方式可靠性差、筛分效率低下、物料筛分率低的难题,本文提出了三种新的振动筛分方案,对不同筛分方案的实际应用效果进行了分析。结果表明三移动一摆动的振动筛分方式对物料的综合分散度最高,稳定性好,该筛分方案已在郭庄煤业选煤厂煤炭筛分过程中得到了全面的应用。 相似文献
8.
Xiang‐Dan Li Zhen‐Xin Zhong Sang‐Hoon Han Seung Hee Lee Myong‐Hoon Lee 《Polymer International》2005,54(2):406-411
From chloromethylated polyimide, a useful starting material for modification of aromatic polyimides, a thermocurable transparent polyimide having acrylate side groups was prepared. In the presence of 1,8‐diazabicyclo[5,4,0]undec‐7‐ene, chloromethylated polyimide was esterified with acrylic acid to synthesize poly(imide methylene acrylate). The polymer was soluble in organic solvent, which makes it possible to prepare a planar film by spin coating. The polymer film became insoluble after thermal treatment at 230 °C for 30 min. Optical transparency of the film at 400 nm (for 1 µm thickness) was higher than 98 % and not affected by further heating at 230 °C for 250 min. Adhesion properties measured by the ASTM D3359‐B method ranged from 4B to 5B. Preliminary results of planarization testing showed a high degree of planarization (DOP) value (>0.53). These properties demonstrate that poly(imide methylene acrylate) could be utilized as a thermocurable transparent material in fabricating display devices such as TFT‐LCD. Copyright © 2004 Society of Chemical Industry 相似文献
9.
Dan Strassberg 《电子设计技术》2005,12(8):66-72
在高达每路2Gbps的数据速率上,几乎没有什么技术能使信号完整性有很大的不同。哪种技术能真正提高性能?或者是只能使性能更差?专家们意见不一。 相似文献
10.